What's the Science Behind...?
Making Shiny Pennies (October 2011 Newsletter)
Why did the pennies look dirty before I put them in the vinegar?
Everything around you is made up of tiny particles called atoms. Some things are made up of just one kind of atom. The copper of a penny, for example, is made up of copper atoms. But sometimes atoms of different kinds join to make molecules. Copper atoms can combine with oxygen atoms from the air to make a molecule called copper oxide. The pennies looked dull and dirty because they were covered with copper oxide.
Why did the vinegar and salt clean the pennies?
Copper oxide dissolves in a mixture of weak acid and table salt-and vinegar is an acid. You could also clean your pennies with salt and lemon juice or orange juice, because those juices are acids, too.
Why do the unrinsed pennies turn blue-green?
When the vinegar and salt dissolve the copper-oxide layer, they make it easier for the copper atoms to join oxygen from the air and chlorine from the salt to make a blue-green compound called malachite.
Soft-Shelled Eggs (November 2011 Newsletter)
Science behind the experiment:
Calcium carbonate in the shell makes eggs hard. The acetic acid in vinegar causes a chemical reaction that releases carbon dioxide (CO2 – the bubbles). This reaction happens until all the carbon is used up, which makes the shell soft.
Take it further:
Leave the soft-shelled egg out on the counter for a day. What happens? (Calcium remaining in the egg re-absorbs carbon from the air and causes the shell to become hard again.)
How Blubber Works (Forthcoming - March 2012 Newsletter)
This experiment was borrowed from Scientific American, December 2011. Follow this link to learn about how adipose fat can act as insulation and to see which concepts you and your child will learn together!